ORLANDO, Fla., March 24 -- Having a particular gene may make African Americans much more sensitive to salt, thereby increasing their risk of developing high blood pressure, according to a new report presented here today at the American Heart Association's epidemiology and prevention meeting.
Researchers say they have found that one variant of the angiotensin converting enzyme (ACE) gene can greatly influence an African American's susceptibility to salt, which is called salt-sensitivity. As little as one extra gram of salt, the amount in half a teaspoon of table salt or the 1,000 milligrams in one serving of some processed foods could raise blood pressure as much as five millimeters of mercury (mm Hg) in people who have the gene variant.
"This is a new finding -- no one has reported this association in African Americans," says the study's lead author, John M. Flack, M.D., professor and associate chairman, department of internal medicine, and director of the cardiovascular epidemiology and clinical applications program at Wayne State University in Detroit. African Americans are at greater risk of developing high blood pressure than the general population.
The body produces angiotensin to restrict blood vessels and help regulate blood pressure. The ACE gene controls the amount of angiotensin released into the body. If the ACE gene is flawed, it can cause the blood vessels to constrict too much, raising the pressure of blood flow on blood vessel walls and, consequently, increasing the risk of high blood pressure.
The researchers examined the influence of the ACE gene variant on blood pressure response to sodium intake in 81 African-American men and women who had normal blood pressure readings (less than 140/90 mm Hg). They found that the systolic blood pressure -- the upper number on a blood pressure reading -- rose sharply in those who consumed sodium and had the ACE gene variant when compared to those who did not have the variant.